A multi-touch display device needs to be tested on its various aspects of performance before leaving the factory, to ensure product quality; for example, a rotation performance of a touch display screen of the multi-touch display device is tested. The rotation performance refers to a performance that, in the presence of a rotation gesture, the touch display screen of the multi-touch display device is capable of detecting the rotation gesture and making a corresponding image rotate according to the rotation gesture.
For example, the testing on the rotation performance of the touch display screen is performed by simulating two fingers of a user with two cylindrical test bars. On the one hand, two test bars of a same diameter are used, a distance between the two test bars is set, then one test bar is fixed and the other test bar rotates around the fixed test bar, a rotation trace of the other test bar detected by the touch display screen is compared with an ideal trace, a deviation value of the rotation trace from the ideal trace is calculated, and quality of the rotation performance of the touch display screen is determined according to the deviation value. On the other hand, two test bars of a same diameter are used, distances between a test position and the two test bars are set respectively, then the two test bars are subjected to concentric rotation around a point indicated by the test position, rotation traces of the two test bars detected by the touch display screen are compared with ideal traces, a deviation value of the rotation trace from the ideal trace is calculated, and quality of the rotation performance of the touch display screen is determined according to the deviation value. Usually, the larger the deviation value, the worse the rotation performance.
However, as described above, during the rotation performance test is performed, the test position for the test bar to perform testing is usually selected at random; and in practice, test results at different positions on a display region of the touch display screen are different. So, the randomly selected test position may result in a less accurate test result.